1. Field of the Invention
The present invention relates generally to a wireless system, and more particularly, to a method and apparatus for transmitting/receiving data streams in a wireless system.
2. Description of the Related Art
A wireless system, such as a digital video broadcasting system, may transmit data in the form of a sequence of frames arranged in a frame structure. A digital video broadcasting system generally uses a Digital Video Broadcasting (DVB) standard, Advanced Televisions Systems Committee (ATSC), Integrated Services Digital Broadcasting (ISDB), or Digital Multimedia Broadcasting (DMB). Each frame typically includes a preamble section and a data section. The preamble section and the data section are time-multiplexed. The data section may be formed as a number of data streams, which may be referred to as Physical Layer Pipes (PLPs). The PLPs may carry, for example, a service such as a video channel provided to a user. Data or data streams from the frames are received using signaling information. The signaling may be referred to as physical layer signaling, or Layer 1 (L1) signaling. The signaling may indicate a modulation or coding scheme that is to be used to receive data. The signaling may, for example, indicate sections of a data field to be decoded, or information necessary for receiving data, such as the location of a data stream within the data section.
Referring to the DVB standard, DVB standard frame structures may provide physical slots within the DVB physical frame structure. For example, DVB Terrestrial 2nd generation (DVB-T2), as a terrestrial standard broadcasting, has a super frame structure consisting of a number of frames. A slot, included in the super frame or each frame, does not transmit a DVB-T2 signal. The super frame is referred to as a Future Extension Frame (FEF). For example, FEF slots may be provided in addition to the parts of the frame structure, which are for transmission of signals intended for reception by conventional fixed DVB receivers.
It has been proposed to use the additional physical slots, such as the FEF slots, for the transmission of signals, such as, for example, signals intended for reception by handheld receivers. For example, UK patent application GB 1100901.6 relates to a system in which data streams may be mapped to logical frames, and the logical frames may be mapped to a sequence of additional physical slots to form a logical channel for transmitting the data streams. The sequence of additional physical slots may include slots within a transmission sequence of more than one radio frequency channel.
It may be desired to transmit a data stream encoded with a multi-transmitter encoding scheme, such as, for example, a Multiple Input Multiple Output (MIMO) encoding scheme or a Multiple Input Single Output (MISO) encoding scheme. However, not all radio frequency channels within the wireless system may be arranged for transmission from multiple antennas. Furthermore, the number of antennas arranged for transmission may vary amongst radio frequency channels. If a data stream encoded with a multi-transmitter encoding scheme is mapped to a logical channel formed from additional physical slots within a transmission sequence of more than one radio frequency channel, the multi-transmitter encoding scheme used by the data stream may not correspond with the number of transmit antennas and/or the multi-transmitter encoding scheme used on at least some of the radio frequency channels. As a result, a restriction may be placed on the formation of a logical channel, so that, for example, a logical channel may be limited to being formed from only those radio frequency channels that use the same multi-transmitter encoding scheme as the data stream.